Centrifugal hammer and renewable tip



Feb. 22, 1966 T, A, RATKOWSK] 3,236,463

Thomas abkowski 3 wag, m4 m q-Hzome Feb. 22, 1966 RATKQWSK] 3,236,463

GENTRIFUGAL HAMMER AND RENEWABLE TIP Filed Jan. 8, 1964 3 Sheets-Sheet 2;L i "i ;;nve ntor ThomasA- Rm. kowski I M57"? I 4 35/ wall/m, and PM gfi .aq-i-kornegs Feb. 22, 1966 'r, ows 3,236,463

CENTRIFUGAL HAMMER AND RENEWABLE TIP Filed Jan. 8, 1964 3 Sheets-Sheet 5vii 1 J33, ZI/aiiue, M4 m )qHLorrze 14,6

United States Patent 3,236,463 CENTRIFUGAL HAMMER AND RENEWABLE TIPThomas A. Ratkowski, Chicago Heights, 111., assignor to American BrakeShoe Company, New York, N.Y., a corporation of Delaware Filed Jan. 8,1964, Ser. No. 336,415 8 Claims. (Cl. 241-197) This invention relates totwo-part hammers for a hammer mill, being of the kind wherein areplaceable tip is removably mounted on the lower end of the hammershank. This application is a continuation-in-part of application SerialNo. 202,181, filed June 13, 1962, entitled, Hammers, now abandoned.

In operating a hammer mill where large size chunks are broken andcrushed to smaller size, the tip of the hammer is the part that displaysthe most wear, and it has become common practice in the art to constructhammers for a hammer mill in such a way that the tip, when unduly worn,can be replaced. The shank of the separable assembly for the most partmerely serves to secure the hammer to the mill shaft for rotationtherewith, and to locate the tip in proper working position within themill.

There is not a great deal of room available within the mill forrepairing the hammer, and in particular when replacing the tip, it isadvantageous to be able to do this quickly without the necessity forremoving the entire hammer assembly from the shaft which carries thehammer.

The primary object of the present invention is to enable these desirableends to be accomplished, and in particular by having resort to aretainer plate welded in place to hold the tip on the hammer, and whichcan be removed incidental to replacing the tip merely by applying atorch to melt the weldment.

Another object of the invention is to secure a replaceable tip on ahammer shank so that an integral wall of the tip prevents transversemovement of the tip relative to the shank in a first direction, and aslidable wall is interfitted into the opposite end of the tip to preventtransverse movement in the opposite direction of the tip relative to theshank so that a mechanical fastening device merely prevents the inwardor vertical sliding movement of the slidable plate. Thus, theinterlocking retainer plate rather than the mechanical fastener securesthe tip against transverse sliding relative to the hammer shank. Morespecifically, in accordance with a further object of the invention, areplaceable tip is secured to the hammer shank by a retainer plate whichis adapted to interlock with the three side walls of the recess in whichthe hammer shank is disposed so that a mechanical locking means such asa fastener or detent which merely retains the retainer plate againstradially inward movement rather serving to hold the tip on the hammershank.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show a preferredembodiment of the present invention and the principles thereof and whatare now considered to be the best mode for applying these principles.Other embodiments of the invention embodying the same or equivalentprinciples may be made as desired by those skilled in the art withoutdeparting from the present invention and the purview of the appendedclaims.

In the drawings:

FIG. 1 is a sectional view of a hammer to which the present invention isapplied;

FIG. 2 is a view illustrating the parts of the hammer of FIG. 1 indisassembled relationship, the tip of the hammer being partly brokenaway;

FIG. 3 is an elevational view of a preferred form of retainer plate;

FIG. 4 is an elevational view of another form of retainer platecontemplated by the present invention;

FIG. 5 is a fragmentary sectional detail View illustrating aspects ofthe retainer plate of FIG. 4 in relation to the tip of the hammer;

FIG. 6 is a fragmentary sectional detail view illustrating the nature ofthe weldments joining the retainer plate to the hammer tip;

FIG. 7 is a front elevational view of another embodiment of theinvention having a retainer plate secured against vertical movement by abent rod;

FIG. 8 is an end elevational View of the rod and retainer plate of theembodiment of the invention shown in FIG. 7;

FIG. 9 is an end elcvational view of a retainer plate held againstvertical movement by a detent;

FIG. 10 is a sectional view of another embodiment of the inventionwherein a bolt secures a retainer plate against vertical movement;

FIG. 11 is a front elevational view of the retainer plate employed withthe embodiment of the invention shown in FIG. 10; and

FIG. 12 is a plan view of the retainer plate of FIG. 11.

The present invention is illustrated as embodied in a hammer 10, FIG. 1,which includes a shank member 11 and a related tip member 12. The tip isformed with a recess extending downwardly from the top thereof, and thelower end of the shank is nested therein.

The hammer shank or arm 11 is of the type to be secured within a hammermill for rotation with the rotor of the mill. Usually, the rotor is inthe form of a disc or plate having a plurality of shafts or supportingpins of large diameter projecting therefrom for carrying a like numberof hammers, and to this end the shank 11 is formed at the head or upperend thereof with a relatively large opening 14 adapted to receive such ashaft or mill pin.

The tip 12 represents that part of the hammer which acts directly on thematerial that is to be crushed or comminuted within the mill. As aresult, the tip 12 tends to wear rather rapidly, and it becomesnecessary periodically to replace the tip. The wearing action is sosevere that the usual tip is cast from austenitic manganese steel.

The shank member 11 and the tip member 12 have complementallyinterfitting parts slidably related to enable the tip to be slipped onand off the lower end of the shank, that is, the end opposite theopening 14, and such sliding movement occurs in a direction normal tothe longitudinal axis of the shank.

To this end, the lower end of the shank member 11 is provided with apair of outwardly projecting shoulders or wings 17 and 18 which projectfrom the leading and trailing faces 19 and 20 of the mill, consideredfrom the path of travel of the hammer in the mill indicated by thecurved arrow in FIG. 1. p The other sides of the hammer shank, such asthe side 21, FIG. 2, face the sides of the mill.

As shown in FIG. 1, the wings or ribs 17 and 18 are positioned above theflat lower face 23 representing the remote face of the shank at the endthereof opposite the shaft opening 14.

The shoulders 17 and 18 are of dovetail form in cross section forreasons to be explained hereinafter and are adapted to neatly fit incomplemental grooves or slots 24 and 25 located within the hammer tip.Thus, the tip 12 is formed with a relatively large recess 26, FIG. 2,extending downwardly thereinto and terminating in a flat face 28 of thehammer tip. In this connection, it may be noted that the tip is ofgenerous size in comparison to the shank so that there is adequate metalfor prolonged use.

In addition to the flat face 28, the tip includes flat vertical fore andaft impacting faces 30 and 31 considered from the standpoint of the pathof rotation of the hammer, and these faces at their lower ends arejoined by an arcuate lower face 33 of the tip having a curvesubstantially complemental to the arcuate interior wall of the millalong which crushing action occurs.

As best shown in FIG. 2, the recess 26 is open at one of the sides ofthe tip which will face the side plate of the mill. It may further beobserved that the cross-sectional geometry of the end of the shankremote from the opening 14 therein, and the complemental geometry of therecess 26, is substantially cruciform. As a consequence, the tip, fromthe exposed side of the tip, FIG. 2, can be easily slid onto the lowerend of the shank in a direction normal to the longitudinal axis of theshank, bringing the mating surfaces of the shank and the tip into fullyseated or nested contact.

The excessive centrifugal forces during operation of the mill might tendto encourage spreading of the end walls 30W and 31W of the hammer tip,but in the present hammer this is resisted by so orienting the uppersurfaces of the projections 17 and 18 as to have the same in planes 17Aand 18A that define acute angles with the adjacent faces 19 and 20 ofthe hammer shank.

The primary aspect of the present invention is that the tip is securedagainst displacement or dismounting relative to the tip, along a pathnormal to the longitudinal axis of the hammer shank, by a flat retainerplate 35 welded in place at the open side of the tip recess that isvisible in FIG. 2. Thus, after the tip has been complementally relatedto the cruciform end of the shank 11, the retainer plate 35 ispositioned in a manner described in detail hereinafter, whereafterweldments are afforded between portions of the retainer plate andadjacent surfaces of the tip to in effect immobilize the tip on the endof the hammer shank.

As was mentioned above, the recess 26 in the tip 12 not only opens atthe top of the tip as viewed in FIGS. 1 and 2, but also opens at one ofthe sides thereof which will lie adjacent one of the side plates of thehammer mill. The opposite side of the recess 26 in the tip 12 is closedby a solid wall 36 that is an integral part of the cast body which isthe tip 12.

The grooves 24 and 25 within the hammer tip recess 26 are defined byspaced ledge elements 37 and 38, and these are foreshortened incomparison to the width of the end walls 30W and 31W of the hammer tip.Resultantly, a pocket 12F, FIGS. 2 and 6, of rectangular area is definedat the open side of the recess in the hammer tip, and the retainer plate35 is dimensioned to fit neatly and entirely therein to afford a wallthat closes off the side of the recess 26 that is opposite the wall 36.

Therefore, after the hammer shank and tip have been complementallyfitted together, the retainer plate 35 is positioned in the pocketaforesaid, and is to be welded to the tip as will now be explained.

The plate 35 at the face thereof that will be outwardly of the hammertip is preferably provided with quarterround recesses or pockets 35F atthe four corners thereof. These pockets expose adjacent surfaces of thetip 12 when the plate 35 is in place, and weldments W, FIG. 6, can bedeposited in such pockets, firmly joining the retainer plate to thehammer tip at the open side of the recess 26 therein. In this manner,the tip is immobilized in its working attitude on the end of the hammershank.

When it is desired to replace a worn tip under and in accordance withthe present invention, it is merely necessary to apply a torch to theaforesaid weldments to melt the same, and the plate 35 can be lifted outof its pocket, permitting the tip to be Withdrawn from the end of theshank in a direction opposite to that in which it was moved onto theshank initially.

As an aid to positioning the retainer plate, it is advantageous toafford a tongue thereon adapted to fit in a corresponding slot in thetip of the hammer in the pocket portion thereof. This will serve totemporarily position the retainer plate during completion of the weldingoperations.

The modified form of retainer plate is identified by reference character40 in FIG. 4, such being identical to the retainer plate 35 describedabove except that a tongue or flange 41 is provided thereon to projectfrom what amounts to the edge thereof which will be adjacent the surface28 of the hammer tip. As shown in FIG. 5, the tongue 41 is preferablytapered and adapted to fit into a complementally shaped receiving slot42 formed in the edge of the surface 28 of the hammer ti correspondingto the plate receiving pocket as 12P defined as aforesaid.

In the embodiment of the invention shown in FIGS. 7, 9, and 10, aretainer plate 50 is disposed to interlock with the tip 12 to preventtransverse sliding of the tip 12 relative to the hammer shank or arm 11.That is, rather than Welding a retainer, such as retainer plate 35 tothe tip 12, as in the embodiments of the invention illustrated in FIGS.1 and 2, the retainer plate 50 of these later embodiments of theinvention has an interfitting relationship with the tip to prevent theretainer plate moving all but vertically and vertical movement islimited by either a bent rod 54-, a detent 56 or a threaded bolt 58.

The recess 26 in the tip 12 has the cruciform geometry of thehereinbefore discussed embodiments of FIGS. 1 and 2, but the pocket 121is provided with a recess 60 in the side wall 30W, and a recess 61 inthe side wall 31W. The recesses 60 and 61 are adapted to receivecomplementary shaped projections 63 and 64 extending outwardly from theopposite sides of the retainer plate 50, FIGS. 11 and 12. Additionally,the retainer plate 50 is provided with a downwardly extending tongue orflange 65 adapted to be disposed in a complementally shaped receivingslot 66 formed in the edge of the bottom surface 28 of the recess 26 inthe hammer tip. Thus, it will be seen that with the shank 11 moved fullyinto the recess 26 to abut the rear side wall 36 and the retainer plate50 disposed to close the open end of the recess 26 in the tip 12 theflanges 63 and 64 will be in their respective grooves 60 and 61, and thebottom tongue 65 will be in its complementally shaped recess 66. Thus,the retainer plate 50 is interlocked with the tip 12 and the shank 11cannot be moved transversely relative to tip 12 due to the retainerplate 58 and the blind end wall 36.

For the purpose of mechanically holding the retainer plate 50 againstradially inward or vertical movement, that would remove the retainer 51from closing the end of the recesses 26, the retainer rod 54 has a firstend 68 bent transversely over the retainer plate 519 and seated within agrooved recess 69 therefor and has its lower end '70 bent transverselyin the opposite direction and seated in a recess 71 therefor in the wallof the hammer shank abutting the interior side '72 of the retainer plate50. As shown in FIG. 8, the retainer plate 51) is provided with alongitudinally extending groove 74 in the interior wall of the retainerplate 50 extending from the recess 69 and to the recess 71 for receivingthe longitudinally extending intermediate portion 75 of the rod 54. Toremove the retainer plate 50, the end 68 of the rod 54 is bent to anupward dotted line position, FIG. 8, and then the retainer plate 50 ismoved vertically upward so that the tip 12 can be slid transversely tothe shank 11.

For the purpose of retaining the retainer plate 50 against verticalmovement in the embodiment of the invention of FIG. 9, there is provideda detent 56, which includes a hemispherically shaped ball 76 of metal orthe like adapted to be seated in a complementary shaped recess 77 formedin the rear surface 72 of the retainer plate 50 at an elevation toreceive the ball 76 when the tongue 65 of the retainer plate 50 isseated in the recess 66. The ball 76 is seated in a recess 79 in thehammer shank 11 and is urged outwardly by a resilient plug 80 of rubberor the like to seat in the recess 77. Preferably, a front face 82 of theretainer 50 is provided with a notch 83, so a pry bar or the like can beinserted in a notch and used to apply sufiicient force to move theretainer plate 50 vertically upward past the detent ball 76.

For the purpose of retaining the retainer plate 59 on the shank 12 inthe embodiment of the invention of FIG. 10, a threaded fastener 58 hasits threaded portion threaded into a plug of rubber or soft metal 85 ina hammer shank 12 opposite an aperture 86 through which extends thefastener 58 when the retainer plate 50 is properly positioned with itstongue 65 in the recess 66. The threaded fastener 58 is seated in anannular recess 88 so that the head 87 of the fastener 58 is protectedduring operation of the hammer in the hammer mill.

It will be seen from the foregoing that in accordance with the presentinvention, the replaceable tip of a twopart hammer of the kind describedis quite conveniently immobilized or secured against displacement by aseparable retainer plate anchored in place at the open side of a recessin the tip which, initially, enables the tip to be mounted on the end ofthe shank with a simple movement transverse to the longitudinal axis ofthe hammer shank. By the same token, it is a relatively simple operationto remove the plate by the use of a torch invariably available. Bydisposing the plate in a pocket afforded at the open side of the recess,the plate is in effect disposed in a protected position and is notexposed to impact by the material being crushed.

Moreover, it will be seen that a retainer plate 50 is mechanicallyinterlocked with the tip 12 to bear the brunt of attempted sliding ofthe tip transversely in a first direction and a blind wall 36 preventstransverse sliding in the opposite direction, upward, that is radiallyinward along a hammer shank attached to a hammer mill, being preventedby a mechanical fastener or detent.

Hence, while I have illustrated and described preferred embodiments ofmy invention, it is to be understood that these are capable of variationand modification, and I therefore do not wish to be limited to theprecise details set forth, but desire to avail myself of such changesand alterations as fall within the purview of the following claims.

I claim:

1. A two-part hammer of the kind to be used in a hammer mill andcomprising a shank member adapted at one end to be supported by a shaftof the mill, and a replaceable tip member formed with a recess extendingdownwardly from the top thereof and terminating in an upwardly disposedface that bounds the bottom of said recess and in which said oppositeend of the shank is to be disposed, said recess being bounded on threesides by an upwardly extending side wall and a pair of opposed endwalls, said members having complemental interfitting cruciform partsslidably related to enable the tip to be mounted on said opposite end ofthe shank, and firmly secured against displacement due to centrifugalforces, by movement of the tip onto the shank in a direction normal tothe longitudinal axis of the shank, said interfitting parts includinginwardly directed projections on the end walls that extend inwardly ofsaid recess, said recess in the tip being open at one side to enable thetip to be moved as aforesaid and the cruciform parts in the tip beingjoined to said side wall and terminating short of the open side of therecess in the tip to define a side pocket, and a separable plate adaptedto be disposed in said pocket to afford a wall closing off the open sideof the recess substantially to immobilize the tip on the shank.

2. A hammer according to claim 1 wherein the plate is recessed at acorner thereof to enable a weld deposit to be laid down therein incontact with an opposed surface of the tip adjacent said pocket.

3. A one-piece cast replaceable tip for a twopart hammer to be used in ahammer mill and comprising a body portion having a pair of end wallseach presenting an impacting face generally in a vertical plane in anoperative position of the tip, and a lower face joining the firstnamedfaces, said body portion having a relatively large recess extendingdownwardly therein from the top of the tip and terminating in anupwardly disposed face that bounds the bottom of said recess, saidrecess being bounded on three sides by an upwardly extending side walland a pair of upwardly extending end walls and being open at the fourthside; inwardly directed projections on the inner faces of said end wallsto alford a sliding fit of the tip with the end of a hammer shank havinga complemental configuration, and said projections commencing at theinner faces of said side wall and extending but part way along theextent of the inner faces of said end walls thereby to afford a pocketat the open side of the recess of said tip adapted to receive a retainerplate affording a wall at and closing off the open side of said recess.

4. A tip according to claim 3 wherein said projections are tapered in anundercut relationship.

5. A two-part hammer of the kind to be used in a hammer mill andcomprising a shank member adapted at one end to be supported by theshaft of the mill and a replaceable tip member formed with a recessextending downwardly from the top end of and terminating in an upwardlydisposed face that bounds the bottom of said recess in which saidopposite end of said shank is to be disposed, said recess being boundedon three sides by an upwardly extending side wall and a pair of opposedend walls, said recess in said tip being open at one side to enable thetip to be moved on the opposite end of said shank, said shank member andtip member having complemental elements constituting a dovetail whenslideably related to each other to firmly secure said tip againstdisplacement from said shank member due to centrifugal force, saidrecess at said open end extending beyond the hammer shank and includingreceiving seats in said opposed end Walls and in said bottom of therecess, a separable plate adapted to be inserted into said recess andhaving portions thereon adapted to be seated in said receiving seats insaid opposed end walls and said bottom of said recess to afford a wallclosing off the open side of the recess substantially to immobilize thetip member on said shank member, and locking means for locking saidretainer plate to said shank member to prevent radial movement of saidseparable plate from closing 01? said recess.

6. The hammer of claim 5 wherein said locking means includes a detentmeans having a complementally shaped recess and a resiliently urged balldisposed in opposing faces of said separable plate and said hammer shankto hold said separable plate within said recess.

7. The hammer of claim 5 wherein said locking means includes threadedseat means in said hammer shank and a threaded fastener is disposedthrough an aperture in said separable plate, and threaded into said seatmeans to hold said separable plate against radial movement from saidrecess.

8. The hammer of claim 5 wherein said locking means includes an aperturein said hammer shank, and a key disposed to have one end in saidaperture and a main body portion extending along a longitudinal surfaceof said hammer shank, and said key having its opposite end bent toextend transversely to overlay the upper end of said separable plate tohold said separable plate against radial movement from said recess.

References Cited by the Examiner UNITED STATES PATENTS ROBERT C.RIORDON, Primary Examiner.

3. A ONE-PIECE CAST REPLACEABLE TIP FOR A TWO-PART HAMMER TO BE USED INA HAMMER MILL AND COMPRISING A BODY PORTION HAVING A PAIR OF END WALLSEACH PRESENTING AN IMPACTING FACE GENERALLY IN A VERTICAL PLANE IN ANOPERATIVE POSITION OF THE TIP, AND A LOWER FACE JOINING THE FIRSTNAMEDFACES, SAID BODY PORTION HAVING A RELATIVELY LARGE RECESS EXTENDINGDOWNWARDLY THEREIN FROM THE TOP OF THE TIP AND TERMINATING IN ANUPWARDLY DISPOSED FACE THAT BOUNDS THE BOTTOM OF SAID RECESS, SAIDRECESS BEING BOUNDED ON THREE SIDES BY AN UPWARDLY EXTENDING SIDE WALLAND A PAIR OF UPWARDLY EXTENDING END WALLS AND BEING OPEN AT THE FOURTHSIDE; INWARDLY DIRECTED PROJECTIONS ON THE INNER FACES OF SAID END WALLSTO AFFORD A SLIDING FIT OF THE TIP WITH THE END OF A HAMMER SHANK HAVINGA COMPLEMENTAL CONFIGURATION, AND SAID PROJECTIONS COMMENCING AT THEINNER FACES OF SAID SIDE WALL AND EXTENDING BUT PART WAY ALONG THEEXTENT OF THE INNER FACES OF SAID END WALLS THEREBY TO AFFORD A POCKECTAT THE OPEN SIDE OF THE RECESS OF SAID TIP ADAPTED TO RECEIVE A RETAINERPLATE AFFORDING A WALL AT AND CLOSING OFF THE OPEN SIDE OF SAID RECESS.